The dorsoventral axis of the Drosophila embryo is induced by a ventrally restricted ligand for the receptor Toll. The Toll ligand is generated by a proteolytic processing reaction, which occurs at the end of a proteolytic cascade and requires the gastrulation defective (gd), nudel, pipe, and windbeutel genes. Here we demonstrate that the GD protein is a serine protease and that the three other genes act to restrict GD activity to the ventral side of the embryo. Our data support a model in which the GD protease catalyzes the ventral activation of the proteolytic cascade that produces the Toll ligand.

Mice lacking JIP1, a scaffold protein that organizes JNK pathway components, were constructed independently by two groups. The proposed in vivo function, however, remains contradictory; One study reported that targeted disruption of the jip1 caused embryonic death due to the requirement of JIP1 for fertilized eggs (Thompson et al. [2001] J. Biol. Chem. 276:27745-27748). In contrast, another group (Whitmarsh et al. [2001] Genes Dev. 15:2421-2432) demonstrated that JIP1-deficient mice were viable and that the JIP1 null mutation inhibited the kainic acid-induced JNK activation and neuronal death. The current study was undertaken to re-elucidate the in vivo roles of JIP1 using newly generated JIP1 knockout mice. Our JIP1-deficient mice were viable and healthy. The transient focal ischemic insult produced by middle cerebral artery occlusion (MCAO) strongly activated JNK in brain of jip1(+/+), jip1(+/-), and jip1(-/-) mice. Increased JNK activity was sustained for more than 22 hr in jip1(+/+) and jip1(+/-), whereas it was repressed rapidly in jip1(-/-). Concomitantly, the infarct volume produced by the ischemic insult in jip1(-/-) was reduced notably compared to that in jip1(+/+) brain. These results suggest that JIP1 plays a pivotal role in regulating the maintenance of phosphorylated JNK and neuronal survival in postischemic brain, but is not essential for JNK activation and early development.

The high-level expression plasmid for streptokinase, pSK100, has been constructed. It contains a tac promoter, an ompA signal sequence, a streptokinase structural gene(skc) and a rrnBT1T2 transcription terminator. E. coli JM109 carrying pSK100 produced about 5,000IU of streptokinase per 1 ml of LB-ampicillin media. About 95% of the expressed streptokinase was secreted into the periplasmic and extracellular fractions. The recombinant streptokinase in high yield and purity may be a potential alternative source for the therapeutic agent.

Streptokinase(SK), a plasminogen activator, is known to have multi‐domain structure. The function of the C‐terminal region of streptokinase was investigated with SK mutants constructed by truncating 26, 33, 37, 40, 41, 46, 47, 70 or 97 amino acid residues from the C‐terminus. The truncated SKs were expressed in E.coli and purified. The 41 residue deletion (SKP373) from the C‐terminus had not effect on the plasminogen activation activity. However, the deletion of 46 amino acid residues (SKP368) resulted in the dramatic reduction of the plasminogen activation efficiency. The result suggests that the C‐terminal peptide from Met369 to Pro373 of SK may play an important role on the plasminogen activation.

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